This invention relates generally to circuit protective systems and especially to a computer-controlled system for protecting one or more electric circuits.
Existing deep-submergence vehicles (DSV's) employ non-computer-controlled circuit breaker systems. Each breaker of a system comprises two current sensors and a current interrupter of the heavy-duty-contactor type so as to protect the outboard circuits which may include various lights, propeller motors, and hydraulic pump motors. These circuits are supplied through two 30-volt DC and two 60-volt DC systems. A non-computer-controlled system may usually include 15 contactors and 35 current sensors.
A sensor and/or a contactor is installed in an oil-filled box, which is disposed outboard of the pressure hull of the DSV, and which may be exposed to 9000 psi pressure or more and temperatures as low as 32.degree. F. Operation of the system in this formidable and marine-exposed environment requires yearly inspection and tri-yearly recalibration of the current sensors, where each inspection and recalibration can be quite expensive and time-consuming. Additionally, the reaction time of the existing circuit breakers, installed in compensated oil-filled boxes, (Dow-Corning-200-1) significantly increases with depth as the viscosity of the fluid materially increases. Hence, by virtue of the calibrated sensors and oil-filled circuit breakers, these prior circuit breaker systems for a DSV are extremely susceptible to malfunction.